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<H2>42.1 Locales and Iostreams</H2>
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<P>Within the C++ standard iostreams, <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B> is a class. Class <B><I>locale</I></B> is used for two distinct purposes:</P>
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<LI><P CLASS="LIST">The formatting layer of iostreams uses <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B> facilities for numeric formatting and character classification.</P></LI>
<LI><P CLASS="LIST">The transport layer uses <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B> facilities for code conversion.</P></LI>
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<P>In the standard iostream class templates, the formatting (stream) layer uses only the <B><I><A HREF="../stdlibref/ctype.html">ctype</A></I></B>, <B><I><A HREF="../stdlibref/num-put.html">num_put</A></I></B>, and <B><I><A HREF="../stdlibref/num-get.html">num_get</A></I></B> facets, while the transport (stream buffer) layer uses only the <B><I><A HREF="../stdlibref/codecvt.html">codecvt</A></I></B> facet. For more information on locales and facets, see <A HREF="24.html">Chapter&nbsp;24</A> and the sections of the <A HREF="../stdlibref/noframes.html"><I>Standard C++ Library Module Reference Guide</I></A> devoted to the <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B> class and the various facets.</P>
<P>Each layer contains its own <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B>, so the code conversion facility can be changed independent of numeric formatting. We simply change the <B><I>locale</I></B> associated with a stream buffer without altering the <B><I>locale</I></B> contained by the stream using that buffer.   On the other hand, changing a stream's <B><I>locale</I></B> also changes the <B><I>locale</I></B> contained by the associated stream buffer.</P>
<P>The base class for all streams, <B><I><A HREF="../stdlibref/ios-base.html">ios_base</A></I></B>, contains a <B><I><A HREF="../stdlibref/locale.html">locale</A></I></B> object. This <B><I>locale</I></B> object can be accessed with the <SAMP>getloc()</SAMP> member function and replaced with the <SAMP>imbue()</SAMP> member function. Similarly, <B><I><A HREF="../stdlibref/basic-streambuf.html">basic_streambuf</A></I></B> also contains a <B><I>locale</I></B> object and it, too, defines <SAMP>getloc()</SAMP> and <SAMP>imbue()</SAMP> member functions  (the latter is <SAMP>protected</SAMP> and <SAMP>virtual</SAMP> and called from the publicly accessible <SAMP>pubimbue()</SAMP> member function).</P>

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